package com.joe.camera2recorddemo.Utils;

import android.content.res.Resources;
import android.opengl.GLES20;
import android.util.Log;

import java.io.InputStream;

public enum GpuUtils {
    ;

    /**
     * 读取Assets中的文本文件
     *
     * @param mRes res
     * @param path 文件路径
     * @return 文本内容
     */
    public static String readText(Resources mRes, String path) {
        StringBuilder result = new StringBuilder();
        try {
            InputStream is = mRes.getAssets().open(path);
            int ch;
            byte[] buffer = new byte[1024];
            while (-1 != (ch = is.read(buffer))) {
                result.append(new String(buffer, 0, ch));
            }
        } catch (Exception e) {
            return null;
        }
        return result.toString().replaceAll("\\r\\n", "\n");
    }

    /**
     * 加载Shader
     *
     * @param shaderType Shader类型
     * @param source     Shader代码
     * @return shaderId
     */
    public static int loadShader(int shaderType, String source) {
        if (source == null) {
            glError(1, "Shader source ==null : shaderType =" + shaderType);
            return 0;
        }
        int shader = GLES20.glCreateShader(shaderType);
        if (0 != shader) {
            GLES20.glShaderSource(shader, source);
            GLES20.glCompileShader(shader);
            int[] compiled = new int[1];
            GLES20.glGetShaderiv(shader, GLES20.GL_COMPILE_STATUS, compiled, 0);
            if (compiled[0] == 0) {
                glError(1, "Could not compile shader:" + shaderType);
                glError(1, "GLES20 Error:" + GLES20.glGetShaderInfoLog(shader));
                GLES20.glDeleteShader(shader);
                shader = 0;
            }
        }
        return shader;
    }

    /**
     * 通过字符串创建GL程序
     *
     * @param vertexSource   顶点着色器
     * @param fragmentSource 片元着色器
     * @return programId
     */
    public static int createGLProgram(String vertexSource, String fragmentSource) {
        int vertex = loadShader(GLES20.GL_VERTEX_SHADER, vertexSource);
        if (vertex == 0) return 0;
        int fragment = loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentSource);
        if (fragment == 0) return 0;
        int program = GLES20.glCreateProgram();
        if (program != 0) {
            GLES20.glAttachShader(program, vertex);
            GLES20.glAttachShader(program, fragment);
            GLES20.glLinkProgram(program);
            int[] linkStatus = new int[1];
            GLES20.glGetProgramiv(program, GLES20.GL_LINK_STATUS, linkStatus, 0);
            if (linkStatus[0] != GLES20.GL_TRUE) {
                glError(1, "Could not link program:" + GLES20.glGetProgramInfoLog(program));
                GLES20.glDeleteProgram(program);
                program = 0;
            }
        }
        return program;
    }

    /**
     * 通过assets中的文件创建GL程序
     *
     * @param res      res
     * @param vertex   顶点作色器路径
     * @param fragment 片元着色器路径
     * @return programId
     */
    public static int createGLProgramByAssetsFile(Resources res, String vertex, String fragment) {
        return createGLProgram(readText(res, vertex), readText(res, fragment));
    }

    private static void glError(int code, Object index) {
        Log.e("C2D", "glError:" + code + "---" + index);
    }

}
